The use of low unsaturation level polyols made from double metal cyanide catalysts in combination with chain extenders in the preparation of thermoplastic elastomers is known. Compositions made with such polyols are disclosed, for example, in U.S. Pat. Nos. 5,096,993 and 5,185,420. Prior to the use of double metal cyanide catalysts for the preparation of high molecular weight polyols, the thermoplastic polyurethane elastomers produced with polyoxyalkylene polyols had poor physical properties, such as being too hard, due to high levels of terminal unsaturation in the polyols used in their production. The thermoplastic polyurethane elastomers disclosed in U.S. Pat. Nos. 5,096,993 and 5,185,420 are thermoplastic elastomers made with polyols having less than 0.04 meq/g of end group unsaturation. These thermoplastic elastomers are taught to have enhanced softness.
Because of their softness, thermoplastic elastomers are frequently used in the construction of automotive interior trim components Automotive manufacturers frequently specify that the elastomers used to produce interior trim components must have adequate long-term stability and resistance to degradation by ultraviolet light and that the elastomers must also meet specific manufacturing specifications for resistance to ultraviolet light exposure, particularly in the case of instrument panels. In order to achieve manufacturing specifications for resistance to ultraviolet exposure, antioxidants, ultraviolet light stabilizing agent(s), and pigment(s) may be added to elastomers.
Additionally, due to the presence of end group unsaturation of previously available polyols with molecular weights greater than 2,000, soft (low durometer) aliphatic thermoplastic urethane elastomers have not been available in a dry castable powder or particle forms. U.S. Pat. Nos. 5,824,738 and 6,187,859 disclose aliphatic urethane elastomer compositions comprising low end group unsaturation, low molecular weight polyols stabilized with one or more ultraviolet stabilizing agents, an antioxidant and pigments. While the performance of such elastomers has been outstanding, the relatively high cost of these elastomers due to their use of aliphatic isocyanates has limited their commercial desirability.
One approach taken to reduce the cost of these aliphatic urethane elastomer compositions is to blend the aliphatic thermoplastic polyurethane with a less expensive polymeric material. However, such blends tend to separate under production conditions. Such separation adversely affects the physical properties of the final product.
U.S. Pat. No. 4,883,837 discloses one technique for producing compatible blends of polyolefins with thermoplastic polyurethanes. In the blends disclosed in U.S. Pat. No. 4,883,837, a modified polyolefin is also included in the blended composition. The blends taught in U.S. Pat. No. 4,883,837 are made up of from 15 to 60 wt. % of polyolefin, from 30 to 70 wt. % thermoplastic polyurethane and from 10 to 35 wt. % modified polyolefin. It is the modified polyolefin which acts a compatibilizing agent for the polyolefin and thermoplastic polyurethane.
U.S. Pat. No. 5,109,050 discloses a composition made up of from 80-99 parts by weight of a thermoplastic polyurethane resin and from 1 to 20 parts by weight of a modified polyolefin resin. Any of the known thermoplastic polyurethane resins may be used in the compositions of U.S. Pat. No. 5,109,050. Any of the known modified polyolefin resins may be used in the compositions of U.S. Pat. No. 5,109,050. The compositions described in U.S. Pat. No. 5,109,050 are taught to be flexible, smooth to the touch and stretchable. It is these properties which are said to make these compositions particularly useful for producing diapers.
U.S. Pat. No. 5,852,118 discloses block copolymers of chemically modified polyolefins with thermoplastic polyurethanes, copolyesters or copolyamides and a coupling agent. The coupling agent is a diisocyanate with blocked or unblocked polyisocyanates. This diisocyanate coupling agent may be used in combination with a co-coupling agent selected from primary amines, secondary amines, diols, diepoxides, amino/hydroxy and amino/epoxy compounds. These block copolymers are useful as compatibilizing blends of polar and non-polar thermoplastic elastomers and for promoting adhesion of thermoplastic elastomers onto various polar engineering resins.
U.S. Pat. No. 5,605,961 discloses homogeneous thermoplastic compositions which include (1) a polyolefin selected from isotactic polypropylene, syndiotactic polypropylene and a blend of isotactic polypropylene and thermoplastic polyurethane and (2) a mixture of from 1 to 99% thermoplastic polyurethane and from 1 to 99% of the reaction product of a modified polyolefin and a polyamide resin.
U.S. Pat. No. 5,623,019 discloses a compatibilized thermoplastic molding composition made up of from 30 to 90% thermoplastic polyurethane, 10 to 70% of a polyolefin having a number average molecular weight of at least 10,000 and a compatibilizing agent which is a copolymer having a number average molecular weight of from 25,000 to 350,000 and containing blocks of monoalkylene arene and either hydrogenated conjugated diene or non-hydrogenated conjugated diene.
U.S. Pat. No. 6,054,533 discloses compatibilized blends of a thermoplastic elastomer and a polyolefin in which the compatibilizing agent is a thermoplastic polyurethane. This thermoplastic polyurethane compatibilizing agent is the reaction product of a substantially hydrocarbon intermediate, a diisocyanate and an amine or diol chain extender. The thermoplastic polyurethane compatibilizing agent is included in an amount of from 0.25 to 15 parts by weight for every 100 parts by weight of thermoplastic elastomer plus polyolefin.
U.S. Pat. No. 6,174,959 discloses compatible blends of from 50 to 99% of an aliphatic thermoplastic polyurethane with from 1 to 50% of a copolymer composed of units derived from ethylene and propylene with 25-35% by weight of the copolymer being derived from propylene units. The polyether polyols used to produce the thermoplastic polyurethanes required in U.S. Pat. No. 6,174,959 may have functionalities no greater than 6 and molecular weights of from 400 up to 20,000. There is no teaching in this disclosure with respect to the unsaturation level of the polyether polyols used to produce the thermoplastic polyurethanes used in these blends.
U.S. Pat. No. 6,235,830 discloses a polyurethane resin for slush molding composed of a thermoplastic polyurethane elastomer, a plasticizer and a compound containing a radical polymerizable unsaturated group. The plasticizer is included in an amount of from 5 to 50 parts by weight per 100 parts by weight of polyurethane elastomer. The compound containing a radical polymerizable unsaturated group is included in an amount of from 0.1 to 10 parts by weight per 100 parts by weight of polyurethane elastomer.
U.S. Pat. No. 6,365,674 discloses thermoplastic polyurethane resins which form compatible blends with polyolefins. The compatibility described therein is taught to be attributable to production of the thermoplastic polyurethane from a reaction mixture which includes a reactive polyolefin containing at least one hydroxyl, amine or carboxylic acid functional group.
U.S. Pat. No. 6,414,081 discloses compatibilized blends of non-polar thermoplastic elastomers and polar thermoplastic polymers such as thermoplastic polyurethanes in which from 1 to 40 parts by weight, based on 100 parts by weight of blend, is a compatibilizer. Suitable compatibilizers include: (1) the condensation reaction product of 10-90 wt. % of functionalized polymer with 10-90 wt. % of polyamide or (2) a blend of 10-90 wt. % functionalized polymer with 10-90 wt. % polyamide or (3) a mixture of (1) and (2).
U.S. Pat. No. 6,469,099 and EP 1,235,879 B1 each disclose compatibilized resin blends which include a thermoplastic polyurethane, a succinimide-based compatibilizing agent containing pendant isocyanate-reactive groups or polyoxyalkylene groups corresponding to a specified structure. The compatibilizing agent is used in amounts ranging from 0.5 wt. % to 20 wt. %, depending upon the particular application for which the product resin will be used.